Asymptotic flatness, little string theory, and holography

We argue that any non-gravitational holographic dual to asymptotically flat string theory in d-dimensions naturally resides at spacelike infinity. Since spacelike infinity can be resovled as a ( d - 1)-dimensional timelike hyperboloid ( i.e., as a copy of de Sitter space in ( d - 1) dimensions), the dual theory is defined on a Lorentz signature spacetime. Conceptual issues regarding such a duality are clarified by comparison with linear dilaton boundary conditions, such as those dual to little string theory. We compute both time-ordered and Wightman boundary 2-point functions of operators dual to massive scalar fields in the asymptotically flat bulk.